1、Designation: D 4671 05Standard Test Methods forPolyurethane Raw Materials: Determination of Unsaturationof Polyols1This standard is issued under the fixed designation D 4671; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods measure unsaturation in polyetherpolyols. (See Note 1.)1.1.1 Test Method A, High-Volume Reage
3、nt MethodUsesabout 50 mLof 0.1 M mercuric acetate reagent in methanol and15 g or more of sample. These test methods use an indicator forcolorimetric determination of an end point. It is recommendedfor polyols with low values (below 0.01 millequivalents pergram (meq/g) of unsaturation where large sam
4、ple sizes arerequired.1.1.2 Test Method B, Low-Volume Reagent MethodUses 2mL of ca. 0.05 M mercuric acetate reagent in methanol andabout1gofsample or less. These test methods use apotentiometric determination of an end point.1.2 This standard does not purport to address all of thesafety concerns, if
5、 any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 883
6、 Terminology Relating to PlasticsE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial Chemicals3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, see Terminology D 883.4. Summary of Test Method4.1 Carbon-to-carbon unsaturate
7、d compounds in the sampleare reacted with mercuric acetate and methanol in a methanolicsolution to produce acetoxymercuricmethoxy compounds andacetic acid.3The amount of acetic acid released in thisequimolar reaction, which is determined by titration withstandard alcoholic potassium hydroxide, is a
8、measure of theunsaturation originally present. Because the acid cannot betitrated in the presence of excess mercuric acetate, due to theformation of insoluble mercuric oxide, sodium bromide isadded to convert the mercuric acetate to the bromide, whichdoes not interfere. Inasmuch as these test method
9、s are based onan acidimetric titration, a suitable correction must be applied ifthe sample is not neutral to phenolphthalein indicator. Takecare to exclude carbon dioxide, which titrates as an acid andgives erroneous results.5. Significance and Use5.1 These test methods are suitable for quality cont
10、rol, asspecification tests, and for research.5.2 Side reactions that form unsaturated compounds inpolypropylene oxides produce small amounts of polymers withonly one hydroxyl group per chain. These unsaturated poly-mers lower functionality and molecular weight, while broad-ening the overall molecula
11、r-weight distribution.6. Interferences6.1 These test methods do not apply to compounds in whichthe unsaturation is conjugated with carbonyl, carboxyl, ornitrile groups. Because water presumably hydrolyzes the reac-tion products to form basic mercuric salts, quantitative resultsare obtained only when
12、 the system is essentially anhydrous.Acetone in low concentrations does not interfere significantly,although its presence can be detrimental to the end point.Inorganic salts, especially halides, must be absent from thesample because even small amounts of salts can nullify thereaction of the mercuric
13、 acetate with the unsaturated com-pound.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.22 on CellularMaterials - Plastics and Elastomers. Test Method A was recommended to ASTM bythe Society of the Plastics Industr
14、y Polyurethane Raw Materials Analysis Commit-tee.Current edition approved March 1, 2005. Published March 2005. Originallyapproved in 1987. Last previous edition approved in 1999 as D 4671 - 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Sigia, S. and Hanna, J.G., “Quantitative Organic Analysis via FunctionalGroups,” John Wiley and Sons, New York, 1979.1*A Summary of Changes section appears at the end
16、of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.TEST METHOD AHIGH-VOLUME REAGENTMETHOD7. Apparatus7.1 Pipet, 50-mL capacity.7.2 Erlenmeyer Flask, 250-mL glass-stoppered.7.3 Balance, 1000-g capacity, 0.1-g sensitivity.
17、7.4 Buret, 50-mL capacity.8. Reagents8.1 Purity of ReagentsUse reagent-grade chemicals in alltests. Unless otherwise indicated, it is intended that all reagentsshall conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are av
18、ailable.4Other grades can be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Mercuric Acetate, Methanol Solution (40 g/L)Dissolve 40 g of mercuric acetate (Hg(C2H3O2)2in sufficientmethanol t
19、o make 1 L of solution and add sufficient glacialacetic acid to require a blank titration of 1 to 10 mL of 0.1 Nalcoholic KOH solution/50 mL of reagent. Usually 3 or 4 dropsof acid are sufficient. Prepare the reagent fresh weekly andfilter before using.8.3 Sodium Bromide (NaBr).9. Procedure9.1 Add 5
20、0 mL of methanol to a sufficient number of250-mL Erlenmeyer flasks to determine the acidity of eachsample in duplicate. Neutralize to a faint pink end point, usinga few drops of phenolphthalein indicator solution and 0.1 Nalcoholic KOH solution.Add 30 g of the sample weighed to thenearest 0.1 g to e
21、ach flask and swirl to effect complete solution.Titrate with 0.1 N alcoholic KOH solution to a pink end pointthat persists for at least 15 s and record the volume of titrant asA.9.2 Pipet 50 mL of the Hg(C2H3O2)2solution into each of asufficient number of 250-mL Erlenmeyer flasks to make allblank an
22、d sample determinations in duplicate. Reserve two ofthe flasks for the blank determination. Into each of the otherflasks, introduce 30 g of the sample weighed to the nearest 0.1g and swirl to effect complete solution. Allow the samples tostand together with the blanks at room temperature for 30 min.
23、Swirl the flasks occasionally. Add 8 to 10 g of NaBr crystals toeach flask and swirl to mix thoroughly. Add approximately 1mL of phenolphthalein indicator solution and titrate immedi-ately with 0.1 N alcoholic KOH solution to a pink end pointthat persists for at least 15 s. Record the volume of titr
24、ant usedfor the samples as D and that used for the blank as E. Thesample titration must not exceed 50 mL of 0.1 N alcoholicKOH solution.10. Calculation10.1 Calculate the concentration of unsaturated compounds,meq/g, as follows:C 5 A 3 N!/W (1)where:A = 0.1 N alcoholic KOH solution required to neutra
25、lizethe sample, mL,N = normality of the alcoholic KOH solution, andW = sample used, g.therefore:Total unsaturation 5 D 2 E!N/W 2 C (2)where:D = alcoholic KOH solution required for titration of thesample, mLE = alcoholic KOH solution required for titration of theblank, average mL, andC = average of r
26、esults from Eq 1, meq of acidity/g ofsample.11. Precision and Bias11.1 PrecisionAttempts to develop a precision and biasstatement for this test method have not been successful. Forthis reason, data on precision and bias cannot be given.Because this test method does not contain a numerical preci-sion
27、 and bias statement, it shall not be used as a referee testmethod in case of dispute.Anyone wishing to participate in thedevelopment of precision and bias data can contact theChairman, Subcommittee D20.22 (Section D20.22.01),ASTM,100 Barr Harbor Dr., PO Box C700, West Conshohocken, PA19428.11.1.1 It
28、 is estimated that duplicate results by the sameanalyst can be considered suspect if they differ by more than0.002.11.2 BiasThe bias for this test method has not yet beendetermined.TEST METHOD BLOW-VOLUME REAGENTMETHOD12. Apparatus12.1 Pipet, 2-mL capacity.12.2 Autotitrator, capable of determining a
29、cidimetric endpoints using a 5-mL buret.12.3 Combination, Glass, pH Electrode, for use with theautotitrator.12.4 Balance, capable of weighing samples to 0.0001 g.12.5 Titration Vessels, 50- to 100-mL capacity.13. Reagents13.1 Purity of ReagentsUse reagent-grade chemicals inall tests. Unless otherwis
30、e indicated, all reagents shall conformto the specifications of the Committee on Analytical Reagentsof the American Chemical Society, where such specificationsare available.4Other grades can be used, provided it is firstascertained that the reagent is of sufficiently high purity topermit its use wit
31、hout lessening the accuracy of the determi-nation.4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Po
32、ole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D467105213.2 Mercuric Acetate, Methanol Solution (ca. 0.05 M)Dissolve 16 g of mercuric acetate (Hg(C2H3O2)2) into 1 L ofreagent-grade methanol and add sufficient glac
33、ial acetic acid torequire a blank titration of 0.5 to 1 mL of 0.05 N methanolicKOH for a 2-mL aliquot. Usually several drops of acid arerequired. Prepare the reagent fresh weekly and filter beforeusing.13.3 Methanolic Potassium Hydroxide Solution (0.05 N)Prepare a 0.05-N solution using reagent-grade
34、 KOH dissolvedin methanol. Standardize using standard procedures with po-tassium hydrogen phthalate.13.4 Methanolic Hydrochloric Acid Solution (0.05 N)Prepare a 0.05-N solution by successively diluting concen-trated acid into methanol. This will introduce less than 0.5 %water in the titration reagen
35、t. Standardize by titrating againstthe 0.05 N methanolic KOH.13.5 Sodium Bromide (NaBr).14. Procedure14.1 Use no more than 0.033 millequivalents (meq) ofunsaturated species for this test. For samples having 0.033meq/g or less, add approximately1gofsample weighed to 0.1mg to a 100-mL titration flask.
36、 If the unsaturation value is notknown for a sample, determine an approximate value by usinga 1-g sample. Use this approximate value to calculate a correctsample size that will contribute no more than 0.033 meq of testsample (See Note 2).NOTE 2This test method requires at least a 2-fold molar excess
37、 ofmercury reagent for quantitative reaction of unsaturated species. If toolarge a sample size is selected, this test method will give inaccurate, lowresults as well as reduced precision. Calculate sample size, g, using thefollowing equation:Sample size 5 0.033/test sample unsaturation (3)14.2 Add 2
38、 mL of mercuric acetate reagent solution andswirl to dissolve the sample completely. Cover with a watchglass and allow to stand for a minimum of 30 min. Add 50 mLof methanol followed by approximately 0.25 g of sodiumbromide crystals.14.3 Titrate using 0.05 N methanolic KOH to the end pointusing an a
39、utomatic titrator.14.4 Titrate a blank using the same procedure but withoutadding sample.14.5 To determine the acidity or basicity of the polyol forcorrecting the results, prepare a sample exactly as above, butomit the mercuric acetate reagent. Titrate, as above, with 0.05N methanolic KOH to the pot
40、entiometric end point. If thesolution is determined to be already past the acid end point,repeat this procedure, but titrate with 0.05 N methanolic HCl.15. Calculation15.1 Calculate the acidity, meq/g, of the sample as follows:VA3 N KOH! / WA5 A (4)where:VA= 0.05 N KOH required to neutralize the sam
41、ple,mL,N (KOH) = normality of the methanolic KOH solution,meq/mL, andWA= weight of sample used, g.15.2 Calculate the basicity, meq/g, of the sample as follows:VB3 N HCl! / WB5 B (5)where:VB= 0.05 N HCl required to neutralize the sample,mL,N (HCl) = normality of the methanolic HCl, meq/mL, andWB= wei
42、ght of sample used, g.15.3 Calculate the unsaturation of the sample, meq/g, asfollows:Unsaturation 5 Vs Vb! 3 N KOH! / WA 1 B (6)where:Vs = 0.05 N KOH required for the unsaturation sample,mL,Vb = 0.05 N KOH required for the unsaturation blank, mL,W = weight of sample, g,B = sample basicity, meq/g, a
43、ndA = sample acidity, meq/g.16. Report16.1 Report the results as the average of duplicates, meq/g,to the nearest 0.001 meq/g.17. Precision and Bias517.1 PrecisionTable 1 is based on a round robin con-ducted in 1997 in accordance with Practice E 180, involvingsix samples (see Table 2 for sample descr
44、iptions) tested byseven laboratories. Each test result was the average of twoindividual determinations obtained on the same day. In eachlaboratory, test results were obtained for each material and thetwo test results for a given material were obtained on twoseparate days.NOTE 3The explanations of r
45、and R in 17.1.1-17.1.3 are intended onlyto present a meaningful way of considering the approximate precision ofthis test method. The data in Table 1 must not be rigorously applied to theacceptance or rejection of material, as those data are specific to the roundrobin and are not representative of ot
46、her lots, conditions, materials andlaboratories. Users of this test method must apply the principles outlinedin Practice E 180 to generate data specific to their laboratory andmaterials, or between specific laboratories. The principles of 17.1.1-17.1.3would then be valid for such data.17.1.1 Repeata
47、bility, rComparing two replicates for thesame material obtained by the same operator using the sameequipment on the same day, the two replicate results will bejudged not equivalent if they differ by more than the r value forthat material.17.1.2 Reproducibility, RComparing two results, each themean o
48、f replicates, for the same material obtained by differentoperators using different equipment in different laboratories ondifferent days, the two results will be judged not equivalent ifthey differ by more than the R value for that material.17.1.3 Any judgment in accordance with 17.1.1 and 17.1.2woul
49、d have an approximate 95 % (0.95) probability of beingcorrect.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D201208.D467105317.2 BiasThere are no recognized standards by which toestimate the bias of this test method.18. Keywords18.1 polyether polyol; polyols; polyurethane raw materials;raw material; titration; unsaturationSUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue,D 4671 - 99, that may impact the use of
